Geo-position technologies in city use research: accuracy evaluation in the context of university students mobility

In the last years the broad potentiality and utility that geo tracking systems can offer have been explored in research fields not only related to geography, but medicine, leisure and tourism as well. Although this technology has been employed in mobility and transportation system analysis, there is still a lack of studies in the urbanism field. This research seeks to evaluate the accuracy of geo-positioning technology tools in the analysis of peoples’ movement and flows in the city. Therefore, we have performed an experiment using Campus Mobility, an open source application for Android smartphones developed by the Mobility, Transport and Territory Studies Group (GEMOTT) of the Autonomous University of Barcelona (UAB) based on SpaceMapper by John Palmer. While activated, the app tracks and records automatically spatiotemporal data from volunteers’ smartphones every two minutes through the GPS. By the end of the experiment, a large dataset with more than 47.000 entries has been generated, including geographical position (latitude and longitude), date and time (timestamp) as well as an anonymous user ID. Additionally to the experiment, a survey has been applied to volunteers in order to contrast and complement results from automatically gathered data and users answers. From the obtained dataset, we have investigated users’ paths, movement and meeting points analytically and graphically, aiming to recognize patterns in volunteers’ displacement and to detect possible anomalous data. For the graphic analyses we have created data visualizations in addition to dynamic maps that have been developed using ArcGIS and CartoDB tools. Both outcomes were combined in order to gain a deep understanding on the shortcomings and possibilities that geo-positioning technology tools offer to urban investigation field. Finally we conclude that, despite minor errors, geo-position technology tools provide new great possibilities for city flows and mobility studies, being able to gather automatically a very large amount of detailed data that would be impossible to collect without an automated process. GPS tracking can be considered a powerful resource for urban studies, although those tools are not entirely accurate if applied to a very small scale analysis

Just one housing bubble? an analysis of spatial segmentation of the residential developments values in Barcelona

Durante el último ciclo inmobiliario, la mayor parte de los países han vivido una burbuja inmobiliaria vinculada a la expansión del crédito, aumentando los valores residenciales drásticamente. Pero el incremento de los valores inmobiliarios así como su sobrevaloración no ha tenido el mismo comportamiento en todos los países afectados, a pesar de la globalización de los mercados financieros. En este sentido, no existen razones teóricas para suponer que dentro de un mismo país, e incluso una misma ciudad dicha inflación/deflación de la burbuja inmobiliaria haya sido uniforme. Por este motivo, la presente investigación analiza si durante la inflación del mercado inmobiliario y su posterior deflación, la variación de los valores residenciales ha sido desigual a lo largo del territorio, en el caso concreto de la ciudad de Barcelona. Además, debido a los efectos de las implicaciones macroeconómicas, la segmentación del mercado residencial en el espacio urbano se habría acentuado formándose pequeñas burbujas inmobiliarias, de manera que no solo existiría una segmentación espacial sino también temporal del mercado inmobiliario. Se ha partido de la hipótesis de que en las zonas donde reside la población con un nivel de renta inferior, éstas han sufrido una mayor variación con respecto al total de la ciudad. Dicha hipótesis está fundamentada en el hecho que son zonas con una alta representación de inmigrantes demandantes de vivienda que ha favorecido que la clase obrera originaria pudiera acceder a viviendas de mejor calidad en otras zonas de la ciudad. A su vez, esta premisa no hubiera sido posible sin la innovación bancaria que ha posibilitado el acceso al crédito a las clases más desfavorecidas, aceptando éstas hipotecas de alto riesgo debido a su poca formación financiera y del mercado inmobiliario. Para desarrollar este trabajo, se ha realizado una revisión literaria sobre el contexto general de la burbuja inmobiliaria en España así como diversos trabajos que han estudiado la segmentación espacial del mercado residencial. Metodológicamente, se ha realizado un análisis descriptivo de la evolución de los valores de viviendas plurifamiliares entre 2004 y 2010 agrupadas por distritos y barriadas, así como la elaboración de varios modelos de regresión lineal para explicar dicha variación. Los resultados obtenidos confirman la hipótesis inicial y sugieren la existencia de una segmentación del mercado inmobiliario en la ciudad de Barcelona.During the last real estate cycle, most countries have experienced a housing bubble linked to the expansion of credit, increasing residential values dramatically. The increase in property values as well as its overvaluation has not had the same behavior in all affected countries despite the globalization of financial markets. In this sense, there is no theoretical reason to suppose that within the same country and even in the same city, inflation or deflation of the housing bubble has been uneven. For this reason, this research analyzes whether during inflation of the housing market and the subsequent deflation, the changes in residential values has been uneven throughout the territory in the case of the city of Barcelona. In addition, due to the effects of the macroeconomic implications, residential market segmentation in urban space would have accentuated forming small housing bubbles, so that not only exist a spatial segmentation but also spatial temporal segmentation of the housing market. From the hypothesis that in areas where the population lives with a lower level of income, they have suffered a greater variation with regard to whole city has. This hypothesis is based on the fact that there are areas with a high representation of immigrants demanding housing which has favored that the native working class could access better quality housing elsewhere in the city. At the same time, this premise would not have been possible without the banking innovation enabling access to credit for the most disadvantaged classes, who accepted these subprime mortgages because of their low financial and housing market training. To develop this work, a literature review on the overall context of the housing bubble in Spain has been done and so several works that studied the spatial segmentation of the residential market. Methodologically, there has been a descriptive analysis of the evolution of the values of multi-family housing between 2004 and 2010, they have been grouped by districts and neighborhoods, and several linear regression models has been developed to explain this variation. The results confirm the initial hypothesis and suggest the existence of a segmentation of the housing market in the city of Barcelona

Just one housing bubble? an analysis of spatial segmentation of the residential developments values in Barcelona

Durante el último ciclo inmobiliario, la mayor parte de los países han vivido una burbuja inmobiliaria vinculada a la expansión del crédito, aumentando los valores residenciales drásticamente. Pero el incremento de los valores inmobiliarios así como su sobrevaloración no ha tenido el mismo comportamiento en todos los países afectados, a pesar de la globalización de los mercados financieros. En este sentido, no existen razones teóricas para suponer que dentro de un mismo país, e incluso una misma ciudad dicha inflación/deflación de la burbuja inmobiliaria haya sido uniforme. Por este motivo, la presente investigación analiza si durante la inflación del mercado inmobiliario y su posterior deflación, la variación de los valores residenciales ha sido desigual a lo largo del territorio, en el caso concreto de la ciudad de Barcelona. Además, debido a los efectos de las implicaciones macroeconómicas, la segmentación del mercado residencial en el espacio urbano se habría acentuado formándose pequeñas burbujas inmobiliarias, de manera que no solo existiría una segmentación espacial sino también temporal del mercado inmobiliario. Se ha partido de la hipótesis de que en las zonas donde reside la población con un nivel de renta inferior, éstas han sufrido una mayor variación con respecto al total de la ciudad. Dicha hipótesis está fundamentada en el hecho que son zonas con una alta representación de inmigrantes demandantes de vivienda que ha favorecido que la clase obrera originaria pudiera acceder a viviendas de mejor calidad en otras zonas de la ciudad. A su vez, esta premisa no hubiera sido posible sin la innovación bancaria que ha posibilitado el acceso al crédito a las clases más desfavorecidas, aceptando éstas hipotecas de alto riesgo debido a su poca formación financiera y del mercado inmobiliario. Para desarrollar este trabajo, se ha realizado una revisión literaria sobre el contexto general de la burbuja inmobiliaria en España así como diversos trabajos que han estudiado la segmentación espacial del mercado residencial. Metodológicamente, se ha realizado un análisis descriptivo de la evolución de los valores de viviendas plurifamiliares entre 2004 y 2010 agrupadas por distritos y barriadas, así como la elaboración de varios modelos de regresión lineal para explicar dicha variación. Los resultados obtenidos confirman la hipótesis inicial y sugieren la existencia de una segmentación del mercado inmobiliario en la ciudad de Barcelona.During the last real estate cycle, most countries have experienced a housing bubble linked to the expansion of credit, increasing residential values dramatically. The increase in property values as well as its overvaluation has not had the same behavior in all affected countries despite the globalization of financial markets. In this sense, there is no theoretical reason to suppose that within the same country and even in the same city, inflation or deflation of the housing bubble has been uneven. For this reason, this research analyzes whether during inflation of the housing market and the subsequent deflation, the changes in residential values has been uneven throughout the territory in the case of the city of Barcelona. In addition, due to the effects of the macroeconomic implications, residential market segmentation in urban space would have accentuated forming small housing bubbles, so that not only exist a spatial segmentation but also spatial temporal segmentation of the housing market. From the hypothesis that in areas where the population lives with a lower level of income, they have suffered a greater variation with regard to whole city has. This hypothesis is based on the fact that there are areas with a high representation of immigrants demanding housing which has favored that the native working class could access better quality housing elsewhere in the city. At the same time, this premise would not have been possible without the banking innovation enabling access to credit for the most disadvantaged classes, who accepted these subprime mortgages because of their low financial and housing market training. To develop this work, a literature review on the overall context of the housing bubble in Spain has been done and so several works that studied the spatial segmentation of the residential market. Methodologically, there has been a descriptive analysis of the evolution of the values of multi-family housing between 2004 and 2010, they have been grouped by districts and neighborhoods, and several linear regression models has been developed to explain this variation. The results confirm the initial hypothesis and suggest the existence of a segmentation of the housing market in the city of Barcelona

Just one housing bubble? an analysys of spatial segmentation of the residencial values over time in Barcelona

During the last real estate cycle most of the countries have experienced a housing bubble linked to the expansion of credit, increasing residential values dramatically. Despite the globalization of financial markets, this increase has not had the same impact on all the countries concerned. For this reason, this research analyzes the spatial variation in property values during this period in the case of the city of Barcelona. From the hypothesis that the areas where the population lives with lower qualifications and general education, and in particular financial education, these areas have had more variation in residential values in relation to those areas inhabited by well-off population. Additionally, these historically disadvantaged areas have been the culmination of the extra-EU immigration, which has incentive the dynamics of the real estate market. To test this hypothesis, it is carried out a descriptive analysis of the evolution of scale multifamily values districts and neighborhoods, as well as an econometric analysis to explain this variation. The results confirm the initial hypothesis and suggest the existence of a spatial segmentation of the housing market during both inflation and deflation of the housing bubble. Namely, the poorest neighborhoods have experienced sharped bubbles and busts compared to wealthy areas of the city

Customized In Situ Functionalization of Nanodiamonds with Nanoparticles for Composite Carbon-Paste Electrodes

The incorporation of nanomaterials on (bio)sensors based on composite materials has led to important advances in the analytical chemistry field due to the extraordinary properties that these materials offer. Nanodiamonds (NDs) are a novel type of material that has raised much attention, as they have the possibility of being produced on a large scale by relatively inexpensive synthetic methodologies. Moreover, NDs can present some other interesting features, such as fluorescence, due to surface functionalization and proved biocompatibility, which makes them suitable for biomedical applications. In addition, NDs can be customized with metallic nanoparticles (NPs), such as silver or gold, in order to combine the features of both. Raw NDs were used as modifiers of sensors due to the electrocatalytic effect of the sp 2 and oxygenated species present on their surface. The aim of this research work is evaluating the applicability of NDs modified with silver (Ag@NDs) and gold (Au@NDs) nanoparticles for the development of a suitable (bio)sensing platform. A complete morphological and electrochemical characterization as a function of the prepared nanocomposite composition was performed in order to improve the electroanalytical properties of the developed (bio)sensors. In the present work, the optimal composition for Au@NDs present on the nanocomposite matrix is 3.5% and the one for Ag@NDs is 1%. Good results were obtained in the evaluation of the optimal composition towards hydrogen peroxide and glucose as a model analyte using a (bio)sensor based on graphite-epoxy-Ag@NDs (17:82:1)

Carbon nanotube-based nanocomposite sensor tuned with a catechol as novel electrochemical recognition platform of uranyl ion in aqueous samples

Unidad de excelencia María de Maeztu MdM-2015-0552This article reports a novel electrochemical recognition platform based on a nanocomposite carbon paste electrode containing carbon nanotubes modified with gold nanoparticles carrying a thiolated catechol for the fast amperometric determination of uranyl ion (UO ) in water. Recognition of UO is accomplished by supramolecular chemistry due to the formation of an inclusion complex between catechol and UO . The amperometric device operates at -0.40 V vs. Ag/AgCl, where the reduction of UO takes place on the electrode surface, covering a linear range from 0.49 to 170 μg L UO in a 0.1 M boric acid buffer solution at pH 5.3. The developed sensing system presents good response towards UO in aqueous environmental samples, with good selectivity over other browsed cations and can be easily reset by simple polishing. This platform has demonstrated to be a potential alternative regarding to the common standard bench-top analytical techniques for the development of in-field devices for in-situ monitoring